More than 500 people have rallied in Melbourne's CBD during a 'Stand with Sudan' protest, calling for an end to human rights atrocities being carried out in the African nation.

The vocal crowd chanted “stop the killings in Sudan” as people marched from the State Library to Parliament House.

The protest is one of many held world-wide, after news of mass civilian killings and rapes spread across the globe, as Sudan slipped further into political instability.

Sudan's 30-year dictatorship ended in April during a political coup when President Omar al-Bashir was overthrown by his Defence Minister Awad Mohamed Ahmed Ibn Auf.

Since then, Sudan-based protesters have demanded he step aside to make way for a civilian-led transitional government and elections. This has led to civil unrest that has been countered by deadly street crackdowns by the military.

Mechanical engineer Mazin Bashir moved to Australia from Sudan one month ago. He joined Saturday's protest because he was worried for the safety of his friends and family back home.

Mazin Bashir wants to return to Sudan and help rebuild his home country. PHOTO: Emilio Lanera

“I have many friends and family still in Sudan... I was in touch with them until the 3rd of June,” Mr Bashir said.

“I haven’t been able to speak to anyone since.”

Sudan's military has tried to prevent news of civilian massacres being reported. Despite an internet shutdown, the global spotlight fell on its human rights abuses on June 3 when Mohamed Mattar, 26, was shot dead by militia as he tried to protect two women from harm at a peaceful protest.

The hashtag #blueforsudan began trending internationally on social media, with people changing their profile pictures to blue squares in honour of Mr Mattar and to raise awareness of the Sudanese crisis.

“Basically it was his (Mr Mattar's) favourite colour and it spreads a message. When people see all this blue...it draws more attention to this cause,” Mr Bashir said.

Melbourne-based protesters were encouraged to wear blue on Saturday in memory of Mr Mattar and the dozens of other people who were slain during the June 3 massacre.

The rally was organised by a group of young people with various African backgrounds. This included Sara Yasir, whose Sudan-based family has been targeted by the military’s violence.